Quoth Mark Walters on Mar 15 at  6:42 pm:
> This moves show to the --exclude=(true|false|flag) naming
> scheme. When `exclude' is false or flag show returns all threads
> that match including those that only match in an excluded message, the
> difference being whether excluded messages are flagged excluded.
> 
> When exclude=true the behaviour depends on whether --entire-threads

s/--entire-threads/--entire-thread/

> is set. If it is not set then show only returns the messages which
> match and are not excluded. If it is set then show returns all
> messages in these threads flagging the excluded messages. The

Parse error.

> rationale is that it is awkward to use a thread with some missing
> messages.
> ---
>  man/man1/notmuch-show.1 |   16 ++++++++++++++--
>  notmuch-client.h        |    1 +
>  notmuch-show.c          |   39 +++++++++++++++++++++++++++++----------
>  3 files changed, 44 insertions(+), 12 deletions(-)
> 
> diff --git a/man/man1/notmuch-show.1 b/man/man1/notmuch-show.1
> index d75d971..801b7f1 100644
> --- a/man/man1/notmuch-show.1
> +++ b/man/man1/notmuch-show.1
> @@ -130,9 +130,21 @@ content.
>  
>  .RS 4
>  .TP 4
> -.B \-\-no-exclude
> +.BR \-\-exclude=(true|false|flag)
> +
> +Specify whether to omit threads only matching search.tag_exclude from
> +the search results (the default) or not. The extra option
> +.B flag
> +includes these messages but marks them with the excluded flag.
> +
> +If --entire-thread is specified then complete threads are returned
> +regardless (with the excluded flag being set when appropriate) but
> +threads that only match in an excluded message are not returned when
> +.B --exclude=true.

I found this a bit confusing.  There are two orthogonal things going
on here: what happens to excluded messages and what happens to
fully-excluded threads.  Is the following table accurate?

         --entire-thread=false
      excl. messages   excl. threads
true       omit            omit
false    include         include
flag   include,flag      include

         --entire-thread=true
      excl. messages   excl. threads
true   include,flag        omit
false    include         include
flag   include,flag      include

(My reasoning: --exclude=false is equivalent to not having any
excludes configured, --exclude=true omits excluded messages from the
seed set and filters them in show_messages, --exclude=flag does not
exclude messages from the seed set nor filter them in show_messages.)

If this is right, then what's the point of having both false and flag
for show?  I'm pretty sure their performance will be
indistinguishable.

> +
> +The default is
> +.B --exclude=true.
>  
> -Do not exclude the messages matching search.exclude_tags in the config file.
>  .RE
>  
>  A common use of
> diff --git a/notmuch-client.h b/notmuch-client.h
> index f4a62cc..e36148b 100644
> --- a/notmuch-client.h
> +++ b/notmuch-client.h
> @@ -99,6 +99,7 @@ typedef struct notmuch_show_format {
>  
>  typedef struct notmuch_show_params {
>      notmuch_bool_t entire_thread;
> +    notmuch_bool_t omit_excluded;
>      notmuch_bool_t raw;
>      int part;
>  #ifdef GMIME_ATLEAST_26
> diff --git a/notmuch-show.c b/notmuch-show.c
> index 05d51b2..20d6635 100644
> --- a/notmuch-show.c
> +++ b/notmuch-show.c
> @@ -812,6 +812,7 @@ show_messages (void *ctx,
>  {
>      notmuch_message_t *message;
>      notmuch_bool_t match;
> +    notmuch_bool_t excluded;
>      int first_set = 1;
>      int next_indent;
>  
> @@ -830,10 +831,11 @@ show_messages (void *ctx,
>  	message = notmuch_messages_get (messages);
>  
>  	match = notmuch_message_get_flag (message, NOTMUCH_MESSAGE_FLAG_MATCH);
> +	excluded = notmuch_message_get_flag (message, NOTMUCH_MESSAGE_FLAG_EXCLUDED);
>  
>  	next_indent = indent;
>  
> -	if (match || params->entire_thread) {
> +	if ((match && (!excluded || !params->omit_excluded)) || params->entire_thread) {
>  	    show_message (ctx, format, message, indent, params);
>  	    next_indent = indent + 1;
>  
> @@ -974,6 +976,12 @@ enum {
>      NOTMUCH_FORMAT_RAW
>  };
>  
> +enum {
> +    EXCLUDE_TRUE,
> +    EXCLUDE_FALSE,
> +    EXCLUDE_FLAG,
> +};
> +
>  int
>  notmuch_show_command (void *ctx, unused (int argc), unused (char *argv[]))
>  {
> @@ -983,10 +991,10 @@ notmuch_show_command (void *ctx, unused (int argc), unused (char *argv[]))
>      char *query_string;
>      int opt_index, ret;
>      const notmuch_show_format_t *format = &format_text;
> -    notmuch_show_params_t params = { .part = -1 };
> +    notmuch_show_params_t params = { .part = -1, .omit_excluded = TRUE };
>      int format_sel = NOTMUCH_FORMAT_NOT_SPECIFIED;
>      notmuch_bool_t verify = FALSE;
> -    notmuch_bool_t no_exclude = FALSE;
> +    int exclude = EXCLUDE_TRUE;
>  
>      notmuch_opt_desc_t options[] = {
>  	{ NOTMUCH_OPT_KEYWORD, &format_sel, "format", 'f',
> @@ -995,11 +1003,15 @@ notmuch_show_command (void *ctx, unused (int argc), unused (char *argv[]))
>  				  { "mbox", NOTMUCH_FORMAT_MBOX },
>  				  { "raw", NOTMUCH_FORMAT_RAW },
>  				  { 0, 0 } } },
> +        { NOTMUCH_OPT_KEYWORD, &exclude, "exclude", 'x',
> +          (notmuch_keyword_t []){ { "true", EXCLUDE_TRUE },
> +                                  { "false", EXCLUDE_FALSE },
> +                                  { "flag", EXCLUDE_FLAG },
> +                                  { 0, 0 } } },
>  	{ NOTMUCH_OPT_INT, &params.part, "part", 'p', 0 },
>  	{ NOTMUCH_OPT_BOOLEAN, &params.entire_thread, "entire-thread", 't', 0 },
>  	{ NOTMUCH_OPT_BOOLEAN, &params.decrypt, "decrypt", 'd', 0 },
>  	{ NOTMUCH_OPT_BOOLEAN, &verify, "verify", 'v', 0 },
> -	{ NOTMUCH_OPT_BOOLEAN, &no_exclude, "no-exclude", 'n', 0 },
>  	{ 0, 0, 0, 0, 0 }
>      };
>  
> @@ -1088,16 +1100,18 @@ notmuch_show_command (void *ctx, unused (int argc), unused (char *argv[]))
>  	return 1;
>      }
>  
> -    /* if format=mbox then we can not output excluded messages as
> -     * there is no way to make the exclude flag available */
> -    if (format_sel == NOTMUCH_FORMAT_MBOX)
> -	notmuch_query_set_omit_excluded_messages (query, TRUE);
> -
>      /* If a single message is requested we do not use search_excludes. */
>      if (params.part >= 0)
>  	ret = do_show_single (ctx, query, format, &params);
>      else {
> -	if (!no_exclude) {
> +	if (format == &format_mbox && exclude == EXCLUDE_FLAG) {
> +	    /* there is no where to mark flagged messages so fall back on

s/no where/nowhere/  Also, s/there/There/ for style consistency.

> +	     * including the excluded messages */
> +	    fprintf (stderr, "Cannot flag excluded messages with format=mbox: fall back on just including them\n");

This is a bit verbose.  How about just "Warning: mbox cannot flag
excluded messages"?  Flag already means that the messages should be
included, so this message states exactly what mbox isn't doing that
you might expect it to.

> +	    exclude = EXCLUDE_FALSE;
> +	}
> +
> +	if (exclude != EXCLUDE_FALSE) {
>  	    const char **search_exclude_tags;
>  	    size_t search_exclude_tags_length;
>  	    unsigned int i;
> @@ -1106,7 +1120,12 @@ notmuch_show_command (void *ctx, unused (int argc), unused (char *argv[]))
>  		(config, &search_exclude_tags_length);
>  	    for (i = 0; i < search_exclude_tags_length; i++)
>  		notmuch_query_add_tag_exclude (query, search_exclude_tags[i]);
> +	    if (exclude == EXCLUDE_FLAG) {
> +		notmuch_query_set_omit_excluded_messages(query, FALSE);
> +		params.omit_excluded = FALSE;
> +	    }
>  	}
> +
>  	ret = do_show (ctx, query, format, &params);
>      }
>